Their are two major Radio-Computer connection channels, CAT and Audio...
The CAT channel allows you to tell the radio what frequency and mode to tune to, which VFO to use and when to transmit and receive. This allows MacLoggerDX running on your computer to automatically tune your radio to a dxcluster spot it has just received. CAT also allows the computer to read back this information so that MacLoggerDX can automatically enter the frequency and mode you are using when you log a call.
Since most radios have old style TTL or RS-232 connections for this channel and most computers have abandoned these old style serial ports, we need to add a USB-to-Serial adapter to the computer. This is usually a simple piece of hardware accompanied by a Mac software driver that allows MacLoggerDX to "see" the radio connected to this device. The device may also include level converters to convert the RS-232 to the TTL level required by the (older) radio and sometimes DTR and RTS lines to also let the computer key the radio's PTT and CW lines.
Some devices combine the above capabilities with digital CW generators and or modems for the Audio channel. Some radios have the USB/Serial adapters built in and only require a USB cable connecting them to the computer but may also require a Mac driver to be installed.
Newer radios have these USB/Serial UARTs built into the radio with a USB connection - they still need a driver.
The audio chanel allows the computer to send pre-recorded speech or digitally encoded information (RTTY, PSK etc.) to the radio's microphone or accessory jack as well as receive digitally encoded data from the radio's headphone or acccesory jack for decoding. Some radios have this sound card capability built into the radio and it can be accessed over the same USB cable as the CAT channel through the System Preferences Sound settings.
If you don't see the USB/Serial adapter port connected to your radio in the Port popup then that means that the Mac cannot see it and you don't have the right driver installed or you have a bad/loose cable from the adapter to your computer, or you have a radio with an internal USB/Serial adapter and the radio is powered down.
You can tell which chip set is being used in your adapter/radio by selecting "About This Mac / Overview / System Report / Hardware / USB. If the UART shows up in the Hardware/USB report It means that it is plugged in and powered up - not that a driver is necessarily loaded. Once you have identified the UART Chip set (FTDI, Silicon Labs, Prolific etc.) you can download and install the Mac driver from the manufacturers web site.
The USB/UART Bridge chip inside the Icom, Yaesu and Kenwood radios is a Silicon Labs USB to UART Bridge Controller and the Mac drivers are available here.
The USB/UART Bridge chip inside the Eagle, K3S and KX3 is an FTDI USB to UART Bridge Controller and the Mac drivers are available here. Note: recent version of Mac OS X include an FTDI driver.
If you have Parallels running on your Mac - make sure it hasn't "stolen" the port.
You may also need to reboot your Mac after the install (If you are installing this driver on High Sierra for the first time, see the section below).
You can tell which driver is installed and loaded by selecting "About This Mac / Overview / System Report / Software / Extensions. and looking for the kernel extension that matches the adapter chip set (eg FTDI, Silicon Labs, Prolific etc.) It’s important that the driver is Loadable and Signed. It will only show as Loaded when the device is powered up and plugged in.
Don’t forget that the System Report does not automatically refresh. If you want to see if a change you made (plugging/unplugging/changing usb ports etc.) has caused the driver to load then you have to go through the system report steps again - or run MacLoggerDX and look at the debug log for the loaded driver.
1 more thing to try...
Summary of Apple Technical Note TN2459
User-Approved Kernel Extension Loading
macOS High Sierra 10.13 introduces a new feature that requires user approval before loading new third-party kernel extensions.
Approval is automatically granted to third-party KEXTs that were already present when upgrading to macOS High Sierra.
When a request is made to load a KEXT that the user has not yet approved, the load request is denied and macOS presents this alert.
This prompts the user to approve the KEXT in System Preferences / Security & Privacy / General
This approval UI is only present in the Security & Privacy preferences pane for 30 minutes after the alert. Until the user approves the KEXT, future load attempts will cause the approval UI to reappear but will not trigger another user alert..
Once approved, the KEXT will immediately be loaded or added to the prelinked kernel cache, depending on what action was blocked. Subsequent requests to load the KEXT will proceed silently as on previous macOS versions.
Note from Scott (KC8KBK) on the QRZ macOS forum...
"Turns out, if the radio is plugged into the USB and turned on the first time you try to load the driver, it won’t load correctly. I un-installed, unplugged my 7300, re-installed the driver, rebooted, then plugged the radio in and turned it on."
Note from Sloan (KN4GQB)...
"That did it! You have to not have the transmitter/radio connected before you install the driver. Once it is all setup on the computer - the radio must be off before you plug in the USB…after that you can turn on the radio, open the program and select the proper driver under prefs…."
The latest word from Silicon Labs ...
"The Mac CP210x driver does indeed work with High Sierra.
Make sure you have taken a look at Apple Technical Note 2459 about changes they made to how Kernel extensions are loaded in High Sierra. If you don't specifically approve every kernel extension, they don't load. The user interface Apple implemented for this new security feature has been confusing for many people. The result has been that the kernel extensions doesn't load and they think it just doesn't work on High Sierra and they don't know why.
I'm not saying that this is for sure the cause of the problem you are seeing, but you should rule it out first.
If you do rule it out and are still having problems, please feel free to post back. Please include the VID/PID of your device when you do that. Thanks."